OFFSET
1,2
COMMENTS
The number of ways to write k as a number of two squares only depends on the parity of the multiplicity of 2, the parity of the multiplicity of a prime of the form 4*m + 3 and the multiplicity of a prime of the form 4*m+1 (See A025426). Terms in this sequence have no prime factors of the form 4*m + 3.
LINKS
David A. Corneth, Table of n, a(n) for n = 1..10000
EXAMPLE
650 = 2*5*13 is in the sequence as its prime factors are 2 or of the form 4*m + 1. It's the least positive integer of the form 2*p*q where p and q are distinct and each of the form 4*m+1.
CROSSREFS
KEYWORD
nonn
AUTHOR
David A. Corneth, Jul 24 2020
STATUS
approved